The statements in this section merely provide background information related to the present disclosure and may not constitute prior art.
In general, a hybrid vehicle is a vehicle that travels by using an engine and a motor as driving sources, and an environmentally-friendly vehicle that travels by using both energy generated from fossil fuel and electrical energy, thereby reducing exhaust gas and improving fuel efficiency.
FIG. 1 schematically illustrates an example of configurations of an engine and a driving motor that are driving sources for driving the hybrid vehicle, and a hybrid power train that includes an engine clutch and a transmission for power transmission.
As illustrated in FIG. 1, a configuration of a power train including a driving system such as an engine, a driving motor, and a power transmission device in the hybrid vehicle includes an engine 1 and a driving motor 3 which are driving sources for driving the vehicle and disposed in series, an engine clutch 2 which is interposed between the engine 1 and the driving motor 3 to transmit power or block power transmission between the engine 1 and the driving motor 3, an inverter 5 which drives and controls the driving motor 3, a transmission 4 which adjusts speed of power of the engine 1 and the driving motor 3 and transmit power to a driving shaft, and a hybrid starter and generator (HSG) 7 which is connected with the engine 1 so as to be able to transmit power to the engine 1.
Among the above configurations, the engine clutch 2 transmits power or blocks power transmission between the engine 1 and the driving motor 3 through a lock-up operation and an opening operation using hydraulic pressure.
A battery 6, which is a power source (electric power source) for the driving motor 3, is connected to the motor through the inverter 5 so as to be charged and discharged, and the inverter 5 converts a direct current of the battery 6 into a three-phase alternating current and applies the three-phase alternating current to the motor to drive the motors 3 and 7.
The hybrid starter and generator (HSG) 7, which is typically connected to the engine through the belt, is provided as a motor with a capacity smaller than that of the driving motor 3, and starts the engine by transmitting its own power to the engine 1 through the belt or generates electricity by using rotational force transmitted from the engine, and the battery 6 is charged with electrical energy that is produced by the operation of generating electricity.
A system in which the hybrid starter and generator (HSG) supplements engine output as a driving source for driving the vehicle without using the driving motor in accordance with the type of vehicle is also known.
A pulley of the hybrid starter and generator is connected with a crank pulley mounted on a crank shaft (C/S) through the belt so as to be able to transmit power therebetween, and the hybrid starter and generator is operated by the motor, and transmits rotational force to the crank shaft through the belt to start the engine.
The hybrid starter and generator is operated as an electric generator during the operation of the engine, and generates electrical energy by receiving rotational force of the engine, that is, rotational force of the crank shaft through the belt, and the battery is charged.
In particular, the hybrid starter and generator is operated as a motor while the vehicle travels, and transmits rotational force to the engine side through the belt, such that torque boosting in which torque of the hybrid starter and generator is provided as driving torque for driving the vehicle may be carried out, and the hybrid starter and generator is operated as an electric generator when the vehicle is braked or coasting, such that energy regeneration in which electrical energy is produced by rotational force transmitted from the engine through the belt and the battery is charged may be carried out.
Meanwhile, when auxiliary machinery components, which includes the hybrid starter and generator (HSG) and are connected with the engine through the belt so as to be able to transmit power, are applied to the engine, an automatic tensioner is mounted to automatically adjust and maintain tension of the belt, that is, the auxiliary machinery belt.
In the engine for a hybrid vehicle, the hybrid starter and generator receives power from the engine and transmits power to the engine through the belt, and a tightened state and a released state of the auxiliary machinery belt are continuously changed depending on an operational condition of the engine and an operational condition of the hybrid starter and generator.
Therefore, two or more existing automatic tensioners are sometimes mounted in the engine, and FIG. 2 illustrates an example in which two mechanical automatic tensioners 16 and 17 are mounted on a single auxiliary machinery belt 15 that is connected between a crank pulley 11 and a pulley 14 of the hybrid starter and generator 13.
However, in a case in which the two mechanical automatic tensioners 16 and 17 are mounted, a layout at a mounting portion of the engine side is complicated, and it may be difficult to mount the two automatic tensioners in accordance with the type of engine.
Because the automatic tensioners are applied in a duplicate manner, tension of the belt may be excessively increased, and as a result, there are problems in that fuel efficiency of the vehicle may deteriorate, and weights and costs may be increased.
In order to solve the above problems, a Ω-type tensioner and a Y-type tensioner have been developed and applied.
International Patent Publication No. WO 2012-049030 (Apr. 19, 2012) discloses the Ω-type tensioner, and the Ω-type tensioner is mounted directly on a surface of a component front surface on which a pulley of an auxiliary machinery component such as a hybrid starter and generator is positioned, and supports a belt at both sides of the pulley.
In the Ω-type tensioner, tensioner pulleys (also called idlers), which are mounted at both ends of an arm that is disposed in a 0 shape, are relatively moved to automatically adjust the tension of the belt that is repeatedly tightened and released.
However, we have discovered that because the Ω-type tensioner needs to be mounted directly on the front surface of the hybrid starter and generator, the Ω-type tensioner has disadvantages in terms of a layout and assembly properties.
Meanwhile, FIGS. 3A and 3B are views illustrating the Y-type tensioner. As illustrated, a Y-type tensioner 20 is a mechanical tensioner that overall has a Y shape, and has a single tension spring 21, a single damping shoe 22, two arms 23a and 23b which are coupled in a Y shape, and tensioner pulleys 24a and 24b which are mounted at ends of the arms 23a and 23b, respectively, and support a belt 15.
The Y-type tensioner 20 has two pivot points that are rotation centers of the arms 23a and 23b, and the arms 23a and 23b relatively moved based on the two pivot points to adjust tension of the belt 15.
The Y-type tensioner has a large size, and we have discovered that as a result, there are problems in that the Y-type tensioner has a disadvantage in terms of a layout, manufacturing costs are high, the Y-type tensioner is heavy in weight, damping force may deteriorate due to abrasion and the like, and durability of the Y-type tensioner is poor.